Excessive ethanol consumption causes an increase in liver protein content. The studies proposed are designed to ascertain the mechanism of this increase by examining intracellular protein turnover rate changes that occur during chronic ethanol consumption. The proposed hypothesis is that chronic ethanol ingestion causes a decrease in the rate of degradation of intracellular hepatic proteins which results in their net accumulation in the liver. The proposed experiments will examine protein synthesis in some detail, but greater emphasis will be given to protein catabolism in the alcoholic animal. The initial objective is to determine the time course of alcohol-induced protein accumulation in livers of rats maintained on a liquid diet containing ethanol. One of two control groups of rats will be pair-fed an identical liquid diet minus ethanol. The second control group will receive a normal (chow) diet. These initial studies will determine the progression of protein accumulation, and the time at which an ethanol-induced 'steady state' of hepatic protein is reached following initiation of ethanol feeding. Protein turnover measurements under both nonsteady state and steady state conditions will then be conducted on total liver and specific subcellular fractions from control and ethanol fed rats. Quantitative immunochemical techniques will also measure turnover rates or specific intracellular proteins. Measurements of in vivo, protein synthesis and degradation will utilize single and dual isotope pulse-labelling techniques. Protein synthesis will be measured by incorporation of [3H]puromycin into nascent polypeptides. Protein catabolism studies during hepatic protein increase (nonsteady state) will examine the kinetics of decay of isotopically prelabelled intracellular proteins. Turnover measurements, conducted under steady state conditions, will utilize dual isotope measurements to further examine differential turnover rate changes in subcellular fractions in the alcoholic state. The proposed studies will provide information on changes in rates of hepatic intracellular protein turnover during ethanol ingestion. They will also allow correlations with, and will serve as a useful prototype for similar studies with other hepatotoxins. Protein accumulation in the liver may contribute to ethanol-induced liver injury since it is associated with hepatomegaly, a common state in the development of alcoholic liver disease.